The contributions of arterial cross-sectional area and time-averaged flow velocity to arterial blood flow

The direct determinants of coronary flow are lumen area and blood flow velocity; however, the precise mechanisms that control these factors are not fully understood. The aim of the present study was to assess by which mechanisms lumen area and coronary flow velocity interact with hemodynamic and morphometric factors, thereby influencing coronary flow. Intracoronary Doppler and ultrasound measurements were performed in 28 patients without coronary lumen irregularities. Flow velocity and lumen cross-sectional area were measured in the proximal segments of all three coronary arteries. Global lumen cross-sectional area and global flow were obtained by adding up the values of all three coronary arteries. Left ventricular mass was assessed by echocardiography. Stress-mass-heart rate and pressure-rate products reflecting myocardial oxygen demand were calculated. Global coronary flow increased during adenosine-induced hyperemia from 197 ± 72 to 637 ± 204 ml/min ( P < 0.001). Global coronary flow closely correlated with the stress-mass-heart rate product ( r = 0.62; P < 0.001). Looking at the two constituents of flow separately, global coronary cross-sectional area was closely related to left ventricular muscle mass ( r = 0.61; P < 0.001), whereas mean coronary flow velocity at rest showed a strong linear relation with the pressure-rate product ( r = 0.64; P < 0.001). There was no interaction between cross-sectional area and blood flow velocity in any of the coronary vessels. Coronary lumen size and flow velocity, the two determinants of coronary flow, are principally determined by different physiological factors. Long-term flow adaptation is achieved by an increase in coronary lumen size, whereas short-term myocardial oxygen requirements are met by changes in resting flow velocity.

Download Full-text

Sequential alterations in the diameters of capillaries in rabbit skeletal muscle following deep transverse friction - a morphometric study

South African Journal of Physiotherapy ◽

10.4102/sajp.v61i2.174 ◽

2005 ◽

Vol 61 (2) ◽

Author(s):

M. A. Gregory ◽

M. N. Deane ◽

M. Marsh

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Muscle Blood Flow ◽

Biceps Femoris ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Biceps Femoris Muscle ◽

Beneficial Effects ◽

The Cross

Objective: The precise mechanisms by which massage promotes repair in injured soft tissue are unknown. Various authorshave attributed the beneficial effects of massage to vasodilation and increased skin and muscle blood flow. The aim of this study was to determine whether deep transverse friction massage (DTF) causes capillary vasodilation in untraumatised skeletal muscle. Setting: Academic institution.Interventions: Twelve New Zealand white rabbits were anaesthetised and the left biceps femoris muscle received 10 minutes of DTF. Following treatment, wedge biopsies were taken from the musclewithin 10 minutes of treatment (R1 - 4), 24 hours (R5 - 8) and 6 days(R9 - 12) after treatment. To serve as controls, similar biopsies weretaken from the right biceps femoris of animals. The samples were fixed, dehydrated and embedded in epoxy resin.Transverse sections (1µm) of muscle were cut, stained with 1% aqueous alkaline toluidine blue and examined with a light microscope using a 40X objective. Images containing capillaries were captured using an image analyser with SIS software and the cross sectional diameters of at least 60 capillaries were measured from each specimen. Main Outcome Measures: Changes in capillary diameter. Results: The mean capillary diameters in control muscle averaged 4.76 µm. DTF caused a significant immediate increase of 17.3% in cross sectional area (p<0.001), which was not significantly increased by 10.0% after 24 hours (p>0.05). Six days after treatment the cross-sectional area of the treated muscle was 7.6% smaller than the controls. Conclusions: This confirms the contention that DTF stimulates muscle blood flow immediately after treatment and this may account for its beneficial effects in certain conditions.

Download Full-text

Changes in lower extremity blood flow during advancing phases of pregnancy and the effects of special footwear

Jornal Vascular Brasileiro ◽

10.1590/1677-5449.002617 ◽

2017 ◽

Vol 16 (3) ◽

pp. 214-219 ◽

Cited By ~ 2

Author(s):

Marta Gimunová ◽

Martin Zvonař ◽

Kateřina Kolářová ◽

Zdeněk Janík ◽

Ondřej Mikeska ◽

...

Keyword(s):

Blood Flow ◽

Venous Blood ◽

Cross Sectional Area ◽

Popliteal Vein ◽

Control Group ◽

Venous Disease ◽

Venous Blood Flow ◽

Sectional Area ◽

Cross Sectional ◽

Experimental Group

Abstract Background During pregnancy, a number of changes affecting venous blood flow occur in the circulatory system, such as reduced vein wall tension or increased exposure to collagen fibers. These factors may cause blood stagnation, swelling of the legs, or endothelial damage and consequently lead to development of venous disease. Objectives The aim of this study is to evaluate the effect of special footwear designed to improve blood circulation in the feet on venous blood flow changes observed during advancing phases of pregnancy. Methods Thirty healthy pregnant women participated in this study at 25, 30, and 35 weeks of gestation. Participants were allocated at random to an experimental group (n = 15) which was provided with the special footwear, or a control group (n = 15). At each data collection session, Doppler measurements of peak systolic blood flow velocity and cross-sectional area of the right popliteal vein were performed using a MySonoU6 ultrasound machine with a linear transducer (Samsung Medison). The differences were compared using Cohen’s d test to calculate effect size. Results With advancing phases of pregnancy, peak systolic velocity in the popliteal vein decreased significantly in the control group, whereas it increased significantly in the experimental group. No significant change in cross-sectional area was observed in any of the groups. Conclusions Findings in the experimental group demonstrated that wearing the footwear tested may prevent venous blood velocity from reducing during advanced phases of pregnancy. Nevertheless, there is a need for further investigation of the beneficial effect on venous flow of the footwear tested and its application.

Download Full-text

Effects of umbilical arterial resistance on its arterial blood ﬂow velocity waveforms

Acta Obstetricia Et Gynecologica Scandinavica ◽

10.1080/j.1600-0412.2001.080004307.x ◽

2001 ◽

Vol 80 (4) ◽

pp. 307-307

Author(s):

Makiko Mine ◽

Junko Nishio ◽

Yuichiro Nakai ◽

Motoharu Imanaka ◽

Sachio Ogita

Keyword(s):

Blood Flow ◽

Flow Velocity ◽

Blood Flow Velocity ◽

Arterial Blood Flow ◽

Arterial Resistance ◽

Arterial Blood

Download Full-text

A Study of Sedimentation at the River Estuary on the Change of Reservoir Storage

E3S Web of Conferences ◽

10.1051/e3sconf/20183103001 ◽

2018 ◽

Vol 31 ◽

pp. 03001 ◽

Cited By ~ 1

Author(s):

Iskahar ◽

Suripin ◽

Isdiyana

Keyword(s):

Flow Velocity ◽

Water Level ◽

Physical Model ◽

River Estuary ◽

Cross Sectional Area ◽

Sectional Area ◽

Sedimentation Pattern ◽

Cross Sectional ◽

Channel Angle ◽

Reservoir Storage

Estuary of the river that leads to the reservoir has characteristics include: relatively flat, there is a change in the increase of wet cross-sectional area and backwater. The backwater will cause the flow velocity to be reduced, so that the grains of sediment with a certain diameter carried by the flow will settle in the estuary of the river. The purpose of this research is to know the distribution and sedimentation pattern at the river estuary that leads to the reservoir with the change of water level in the reservoir storage, so the solution can be found to remove / reduce sediment before entering the reservoir. The method used is the experimental, by making the physical model of the river estuary leading to the reservoir. This study expects a solution to reduce sedimentation, so that sedimentation can be removed / minimized before entering the reservoir. This research tries to apply bypass channel to reduce the sedimentation at the river estuary. Bypass channels can be applied to overcome sedimentation at the river estuary, but in order for the sediment to be removed optimally, it is necessary to modify the mouth of bypass channel and channel angle.

Download Full-text

Alterations of mature arterioles associated with chronically reduced blood flow

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.264.1.h40 ◽

1993 ◽

Vol 264 (1) ◽

pp. H40-H44 ◽

Cited By ~ 3

Author(s):

D. H. Wang ◽

R. L. Prewitt

Keyword(s):

Blood Flow ◽

Vascular Wall ◽

Cross Sectional Area ◽

Sectional Area ◽

Adaptive Responses ◽

Total Blood ◽

Cross Sectional ◽

Old Rats ◽

Total Blood Flow ◽

Autoregulatory Mechanism

Adaptive responses of mature arterioles were examined after a 38% reduction in total blood flow to the cremaster muscle produced by unilateral orchidectomy in 12-wk-old rats. Four weeks later, the muscle was smaller than the contralateral cremaster, which did not increase in size during this period. Measured by closed-circuit television microscopy, the internal diameters of first- through fourth-order arterioles (1A-4A) were smaller, but wall cross-sectional area was reduced only in 3As. The smaller diameter of the 1A in the orchidectomy muscle resulted in unchanged wall shear rate. As determined from the perfusion-fixed, microfilled cremaster muscles, the total length of the arcading arterioles and the number of 3As were not statistically different, but the total number of 4As was significantly reduced on the orchidectomy side. Therefore, chronic load reduction in a mature muscle resulted in reduced blood flow, decreased number of 4As, and smaller arteriolar internal diameters in the absence of net changes in vascular wall cross-sectional area. A local autoregulatory mechanism related to flow-induced shear stress is suggested as the mechanism mediating the changes.

Download Full-text